SQL Server常用的性能诊断语句

/*
常规服务器动态管理对象包括：
dm_db_*：数据库和数据库对象
dm_exec_*：执行用户代码和关联的连接
dm_os_*：内存、锁定和时间安排
dm_tran_*：事务和隔离
dm_io_*：网络和磁盘的输入/输出
*/

--- 运行下面的 DMV 查询以查看 CPU、计划程序内存和缓冲池信息。
select
    cpu_count,
    hyperthread_ratio,
    scheduler_count,
    physical_memory_in_bytes / 1024 / 1024 as physical_memory_mb,
    virtual_memory_in_bytes / 1024 / 1024 as virtual_memory_mb,
    bpool_committed * 8 / 1024 as bpool_committed_mb,
    bpool_commit_target * 8 / 1024 as bpool_target_mb,
    bpool_visible * 8 / 1024 as bpool_visible_mb
from sys.dm_os_sys_info

--- 高I/O开销的查询  Identifying Most Costly Queries by I/O
 SELECT TOP 10
      [Average IO] = (total_logical_reads + total_logical_writes) / qs.execution_count
    , [Total IO] = (total_logical_reads + total_logical_writes)
    , [Execution count] = qs.execution_count
    , [Individual Query] = SUBSTRING (qt.text,qs.statement_start_offset/2,
             (CASE WHEN qs.statement_end_offset = -1
                THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2
              ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)
            ,[Parent Query] = qt.text
    , DatabaseName = DB_NAME(qt.dbid)
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt
ORDER BY [Average IO] DESC;

--- 高CPU开销的查询 Identifying Most Costly Queries by CPU
 SELECT TOP 10
      [Average CPU used] = total_worker_time / qs.execution_count
    , [Total CPU used] = total_worker_time
    , [Execution count] = qs.execution_count
    , [Individual Query] = SUBSTRING (qt.text,qs.statement_start_offset/2,
             (CASE WHEN qs.statement_end_offset = -1
                THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2
              ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)
    , [Parent Query] = qt.text
    , DatabaseName = DB_NAME(qt.dbid)
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt
ORDER BY [Average CPU used] DESC;

--- 高开销的缺失索引 Cost of Missing Indexes
 SELECT  TOP 10
        [Total Cost]  = ROUND(avg_total_user_cost * avg_user_impact * (user_seeks + user_scans),0)
        , avg_user_impact
        , TableName = statement
        , [EqualityUsage] = equality_columns
        , [InequalityUsage] = inequality_columns
        , [Include Cloumns] = included_columns
FROM        sys.dm_db_missing_index_groups g
INNER JOIN    sys.dm_db_missing_index_group_stats s
       ON s.group_handle = g.index_group_handle
INNER JOIN    sys.dm_db_missing_index_details d
       ON d.index_handle = g.index_handle
ORDER BY [Total Cost] DESC;

--- 最常执行的查询 Identifying Queries that Execute Most Often
 SELECT TOP 10
 [Execution count] = execution_count
,[Individual Query] = SUBSTRING (qt.text,qs.statement_start_offset/2,
         (CASE WHEN qs.statement_end_offset = -1
            THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2
          ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)
,[Parent Query] = qt.text
,DatabaseName = DB_NAME(qt.dbid)
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt
ORDER BY [Execution count] DESC;

--- 重复编译的查询（plan_generation_num 指示该查询已重新编译的次数）
select top 25
      sql_text.text,
      sql_handle,
      plan_generation_num,
      execution_count,
      dbid,
      objectid
from sys.dm_exec_query_stats a
      cross apply sys.dm_exec_sql_text(sql_handle) as sql_text
where plan_generation_num > 1
order by plan_generation_num desc

--- 服务器等待的原因 SQL Query Records Causes of Wait Times
 SELECT TOP 10
 [Wait type] = wait_type,
 [Wait time (s)] = wait_time_ms / 1000,
 [% waiting] = CONVERT(DECIMAL(12,2), wait_time_ms * 100.0
               / SUM(wait_time_ms) OVER())
FROM sys.dm_os_wait_stats
WHERE wait_type NOT LIKE '%SLEEP%'
ORDER BY wait_time_ms DESC;

--- 读和写 Identifying the Most Reads and Writes
SELECT TOP 10
        [Total Reads] = SUM(total_logical_reads)
        ,[Execution count] = SUM(qs.execution_count)
        ,DatabaseName = DB_NAME(qt.dbid)
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt
GROUP BY DB_NAME(qt.dbid)
ORDER BY [Total Reads] DESC;

SELECT TOP 10
        [Total Writes] = SUM(total_logical_writes)
        ,[Execution count] = SUM(qs.execution_count)
        ,DatabaseName = DB_NAME(qt.dbid)
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt
GROUP BY DB_NAME(qt.dbid)
ORDER BY [Total Writes] DESC;

--- 运行下面的 DMV 查询以查找 I/O 闩锁等待统计信息。
select wait_type, waiting_tasks_count, wait_time_ms, signal_wait_time_ms, wait_time_ms / waiting_tasks_count
from sys.dm_os_wait_stats
where wait_type like 'PAGEIOLATCH%'  and waiting_tasks_count > 0
order by wait_type

-- 查看SQL阻塞信息
with tmp as (
    select * from master..sysprocesses t where t.blocked != 0
    union all
    select b.* from master..sysprocesses b
        join tmp t on b.spid = t.blocked
)
select t.spid, t.blocked, t.status, t.lastwaittype, t.waitresource, t.waittime
    , DB_NAME(t.dbid) DbName, t.login_time, t.loginame, t.program_name, dc.text
from (select spid from tmp group by spid) s
    join master..sysprocesses t on s.spid = t.spid
    cross apply master.sys.dm_exec_sql_text(t.sql_handle) dc

--kill 53;

-- 查看所有会话的状态、等待类型及当前正在执行SQL脚本
select t.spid, t.kpid, t.blocked, t.status, t.lastwaittype, t.waitresource, t.waittime
    , DB_NAME(t.dbid) DbName, t.last_batch, t.loginame, t.program_name, t.hostname, t.hostprocess
    , t.cmd, t.stmt_start, t.stmt_end, t.request_id, dc.text
from    master.sys.sysprocesses t  

    outer apply master.sys.dm_exec_sql_text(t.sql_handle) dc
where    t.spid >= 50

select s.spid, s.kpid, s.blocked, s.hostname, s.hostprocess, s.program_name, s.loginame
       , s.status, s.lastwaittype, s.waitresource, s.waittime
       , t.transaction_id, t.name, t.transaction_begin_time, dc.text
   from sys.sysprocesses s
      join sys.dm_tran_session_transactions st on s.spid = st.session_id
      join sys.dm_tran_active_transactions t on st.transaction_id = t.transaction_id
      outer apply master.sys.dm_exec_sql_text(s.sql_handle) dc

---补充，查看所有会话当前持有和申请的锁资源(选择在特定的业务库执行，测试模拟，建议将隔离级别改为可重复读)

set transaction isolation level repeatable read

select  l.request_session_id,
          l.resource_type,
          l.resource_subtype,
          l.request_status,
          l.request_mode,
          l.resource_description,
          db_name(l.resource_database_id) as dbName,
          case l.resource_type
              when 'database' then DB_NAME(l.resource_database_id)
              when 'object' then object_name(l.resource_associated_entity_id)
              else OBJECT_NAME(p.object_id)
          end as obj_name,
          p.index_id,
          l.request_lifetime
  from sys.dm_tran_locks l
      left join sys.partitions p on l.resource_associated_entity_id = p.hobt_id
  order by l.request_session_id, l.resource_type

---查看所有会话的 找到活动事务对应的执行语句
select  dc.session_id,
        ds.login_name,
        ds.login_time,
        dc.connect_time,
        dc.net_transport,
        dc.client_net_address,
        ds.host_name,
        ds.program_name,
        case ds.status  when 'sleeping' then '睡眠 - 当前没有运行任何请求 '
                        when 'running'  then '正在运行 - 当前正在运行一个或多个请求 '
                        when 'Dormancy' then '休眠 – 会话因连接池而被重置，并且现在处于登录前状态'
                        when 'Pre-connected' then '预连接 - 会话在资源调控器分类器中'
                        end as status ,
        ds.cpu_time as cpu_time_ms,
        ds.memory_usage*8 as memory_kb,
        ds.total_elapsed_time as total_elapsed_time_ms,
        case ds.transaction_isolation_level when 0 then '未指定'
                                            when 1 then '未提交读取'
                                            when 2 then '已提交读取'
                                            when 3 then '可重复'
                                            when 4 then '可序列化'
                                            when 5 then '快照'
                                        end '会话的事务隔离级别',
        dt.text
from sys.dm_exec_connections  dc        --执行连接，最近执行的查询信息
cross apply sys.dm_exec_sql_text(dc.most_recent_sql_handle) dt
join sys.dm_exec_sessions ds  on dc.session_id=ds.session_id
where ds.login_name= 'LCGS609999'
--where ds.program_name = '.Net SqlClient Data Provider'
ORDER BY dt.text

--清除buffer pool里的所有缓存数据
DBCC DROPCLEANBUFFERS
GO
--清除buffer pool里的所有缓存的执行计划
DBCC FREEPROCCACHE
GO

--统计信息、执行计划

SET STATISTICS IO ON
SET STATISTICS TIME ON
SET STATISTICS PROFILE ON

-- 检查分析死锁信息

1、使用sql profiler 抓取死锁链及图
2、跟踪分析SQL ErrorLog日志

dbcc traceon (1204, 3605, -1)
go
dbcc tracestatus(-1)
go

参考资料：
http://support.microsoft.com/zh-cn/kb/832524

-- 检查分析闩锁等阻塞信息

WHILE 1=1
BEGIN
   EXEC master.dbo.sp_blocker_pss80        -- or sp_blocker_pss08
   -- Or for fast mode
   -- EXEC master.dbo.sp_blocker_pss80 @fast=1
   -- Or for latch mode
   -- EXEC master.dbo.sp_blocker_pss80 @latch=1
   WAITFOR DELAY '00:00:15'
END
GO

cmd执行命令：
osql -E -Sserver -icheckblk.sql -ocheckblk.out -w2000

参考资料：
http://support.microsoft.com/zh-cn/kb/271509

揭开隐藏数据的面纱，优化应用程序性能
https://msdn.microsoft.com/zh-cn/magazine/cc135978.aspx